The invention relates to measuring or testing devices having rotating members, electrical circuits or electrical output means and pickup coils. More in particular, the invention relates to measuring or testing devices having rotors also called herein rotary pistons which rotate in chambers or cylinders which inter-engage.
The background art shows the use of inter-engaging rotary pistons and flowmeters, wherein electrical output is created using pickup coils. However, there is a need in this art for less complicated and more accurate measuring devices. U.S. Pat. No. 4,295,369 shows the use of inter-engaging rotary pistons utilizing a magnetic drive to generate the electrical pulse. This patent exemplifies the number of moving parts that is generally necessary to effect an accurate metering. In this example, magnets are used to drive other magnets which rotate a shaft which create the pulse.
Instead of magnets, often the inter-engaging rotary pistons are coupled to gearings which will effect a metering. U.S. Pat. No. 294,026 is one such example.
A need exists within this art for less moving parts and more accurate metering.
The problem's enumerated in the foregoing are not intended to be exhaustive, but are rather believed to be among many which may tend to impair the effectiveness of previously known meters. Other noteworthy problems may also exist; however, those presented above should be sufficient to demonstrate that the gear meter systems which appear in the art have not been all together satisfactory as the need to use smaller rotary piston meters has developed.
Recognizing the need for an improved arrangement for rotary piston flowmeters, it would be advantageous to provide rotary pistons which are mounted without bearings on fixed shafts thus eliminating the need for expensive bearings. Furthermore, it would be advantageous to have a flowmeter wherein the only moving parts are the rotary pistons. Moreover, there is no requirement for moving parts outside the case as the information is transmitted by means of the magnetic field's effect on the external pickup.